Data point: esim4travel worked fine last week. 3GB, 30 days for about 4 USD, data only. Home carrier was China Mobile HK and it roamed on au with 5G. Interestingly, the IP address showed up as being in Tokyo and all my ads were in Japanese.

I had forgotten to switch off updates over mobile (my home plan has 500GB/mo) and burned through it all in 36 hours so I switched to my 3HK SIM, which spent a couple hours bouncing in and out of LTE service on Rakuten before grabbing a solid au 5G connection for the rest of the trip. HK IP address as expected.